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United States Patent |
5,321,411
|
Tsukamoto
,   et al.
|
June 14, 1994
|
Planar antenna for linearly polarized waves
Abstract
A planar antenna for linearly polarized waves includes a grounding
conductor plate, a power supply circuit plate having a pattern of power
supplying circuit of conductor strips each including power supply
terminals, and a radiation plate having apertures forming radiation
elements, the respective plates being arranged sequentially with an
insulating layer interposed between adjacent ones of the plates to
separate them to be independent of one another through a predetermined
interval, while arranging the power supplying terminals of the power
supplying circuit pattern as well as the apertures in the radiation plate
so that the respective power supply terminals terminate to be within a
contour of the apertures, in a top plan view, whereby the planar antenna
makes it possible to receive at a high gain the linearly polarized waves
over a wide band.
Inventors:
|
Tsukamoto; Katsuya (Kadoma, JP);
Inoue; Hirowo (Kadoma, JP);
Okuno; Kaname (Kadoma, JP);
Abiko; Toshio (Kadoma, JP)
|
Assignee:
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Matsushita Electric Works, Ltd. (Osaka, JP)
|
Appl. No.:
|
007811 |
Filed:
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January 22, 1993 |
Foreign Application Priority Data
| Jan 26, 1990[JP] | 2-17137 |
| Jun 26, 1990[JP] | 2-167841 |
| Jun 26, 1990[JP] | 2-167842 |
Current U.S. Class: |
343/700MS; 343/770 |
Intern'l Class: |
H01Q 001/38; H01Q 013/10 |
Field of Search: |
343/700 MS,786,767,770,829,845,846,847,848,769
|
References Cited
U.S. Patent Documents
4259670 | Mar., 1981 | Schiavone | 343/829.
|
4429313 | Jan., 1984 | Muhs, Jr. et al. | 343/771.
|
4443802 | Apr., 1984 | Mayes | 343/729.
|
4475107 | Oct., 1984 | Makimoto et al. | 343/700.
|
4614947 | Sep., 1986 | Rammos | 343/786.
|
4626865 | Dec., 1986 | Rammos | 343/786.
|
4761654 | Aug., 1988 | Zaghloul | 343/700.
|
4816835 | Mar., 1989 | Abiko et al. | 343/700.
|
4827276 | May., 1989 | Fukuzawa et al. | 343/786.
|
4851855 | Jul., 1989 | Tsukamoto et al. | 343/700.
|
4857938 | Aug., 1989 | Tsukamoto et al. | 343/700.
|
4899162 | Feb., 1990 | Bayetto et al. | 343/700.
|
4922263 | May., 1990 | Dubost et al. | 343/797.
|
4929959 | May., 1990 | Sorbello et al. | 343/700.
|
4977406 | Dec., 1990 | Tsukamoto et al. | 343/700.
|
5005019 | Apr., 1991 | Zaghloul et al. | 343/700.
|
5025264 | Jun., 1991 | Stafford | 343/770.
|
Other References
Ito et al., "Planar Antennas for Satellite Reception", IEEE Transactions on
Broadcasting, vol. 34, No. 4, Dec. 1988, pp. 457-464.
|
Primary Examiner: Hajec; Donald
Assistant Examiner: Le; Hoanganh
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis
Parent Case Text
This application is a continuation of application Ser. No. 07/636,256,
filed Dec. 31, 1990 now abandoned.
Claims
What is claimed is:
1. A planar antenna for linearly polarized waves, comprising
a grounding conductor plate,
a power supply circuit plate having thereon a power supply circuit pattern
including power supply terminals and separated from said grounding
conductor plate by a predetermined space so as to be insulated with
respect to the grounding conductor plate with a layer of dielectric
material interposed between the power supply circuit plate and the
grounding conductor plate, and
a radiation plate having therein apertures disposed as radiation elements
respectively and electromagnetically coupled with each of said power
supply terminals of said power supply circuit plate and disposed to be
separated from the power supply circuit plate by a predetermined space so
as to be insulated with respect to the power supply circuit plate with a
layer of dielectric material interposed between the radiation plate and
the power supply circuit plate,
wherein said radiation plate comprises a metal plate of a thickness smaller
than that of said layer of dielectric material between the radiation plate
and the power supply circuit plate, and having said apertures which
penetrate through said metal plate to be without any patch elements within
and above a zone of said electromagnetic coupling, and said power supply
terminals of said power supply circuit plate are disposed to terminate
within a contour of the apertures in top plan view.
2. The antenna according to claim 1 wherein said apertures are formed in a
square shape.
3. The antenna according to claim 1 wherein said apertures are formed in a
circular shape.
4. The antenna according to claim 1 wherein said power supply circuit
pattern of said power supply circuit plate includes portions in which
power supplying conductor strips are made smaller in their width than that
in other portions of the pattern, said smaller width portions being
adjacent to said power supply terminals to be electromagnetically coupled
to said apertures in said radiation plate.
5. The antenna according to claim 1 wherein said power supply terminals of
said power supply circuit plate are disposed to extend beyond the center
of said apertures in said radiation plate, in said top plan view.
6. The antenna according to claim 1 wherein said layer of dielectric
material comprises a foamed plastic.
7. A planar antenna for linearly polarized waves, comprising
a grounding conductor plate,
a power supply circuit plate having thereon a power supply circuit pattern
including power supply terminals and separated from said grounding
conductor plate by a predetermined space so as to be insulated with
respect to the grounding conductor plate with a layer of dielectric
material interposed between the power supply circuit plate and the
grounding conductor plate, and
a radiation plate having therein apertures disposed as radiation elements
respectively and electromagnetically coupled with each of said power
supply terminals of said power supply circuit plate and disposed to be
separated from the power supply circuit plate by a predetermined space so
as to be insulated with respect to the power supply circuit plate with a
layer of dielectric material interposed between the radiation plate and
the power supply circuit plate,
wherein said radiation plate comprises a metal plate of a thickness smaller
than that of said layer of dielectric material between the radiation plate
and the power supply circuit plate, and having said apertures which
penetrate through said metal plate to be without any patch elements within
and above a zone of said electromagnetic coupling, and said power supply
terminals of said power supply circuit plate are disposed to terminate
within a contour of the apertures in top plan view wherein said layer of
dielectric material comprises a plastic sheet having thereon a plurality
of swellings with air sealed therein and made to stand closely to each
other.
Description
BACKGROUND OF THE INVENTION
This invention relates to planar antennas and, more particularly, to a
planar antenna capable of receiving linearly polarized waves at a high
gain over a wide band.
The planar antenna of the kind referred to are effectively utilized in
receiving the linearly polarized waves transmitted with a relatively wide
band utilized from geostationary broadcasting and communication satellites
launched into cosmic space.
DESCRIPTION OF RELATED ART
Parabolic antennas erected on the roof or the like positions of house
buildings have been generally widely utilized as the antenna for receiving
radio waves transmitted from the satellites, but the parabolic antennas
have been defective in that they are susceptible to strong wind to easily
fall down due to their bulky three dimensional structure so that
additional means for stably supporting them will have to be employed, and
that such supporting means further requires high mounting costs and still
troublesome installation labor.
In attempt to eliminate these problems of the known parabolic antennas,
there has been suggested in U.S. Pat. No. 4,475,107 to T. Makimoto et al.
a planar antenna which is flattened in the entire configuration, according
to which the structure can be much simplified and it is made possible to
directly mount the antenna on an outer wall or the like position of the
house buildings so as to be made inexpensive. Further, prior to the
present invention, the present inventors K. Tsukamoto et al. have
suggested as disclosed in U.S. Pat. No. 4,851,855 a planar antenna in
which power supply circuit and radiation circuit are coupled
electromagnetically to each other rather than being brought into direct
contact with each other, for supplying a power from the power supply
circuit to the radiation circuit, while both circuits as well as a
grounding conductor plate are mutually separated with a space retaining
means. With this arrangement, the power supply circuit can be also
disposed in the space thus retained, and the insertion loss can be reduced
effectively.
According to these U.S. Pat. No. 4,851,855, it is possible to reduce the
insertion loss of the planar antennas and to improve them in the
assembling ability in contrast to any known planar antennas. In this
patent, however, the radiation circuit comprises slots of square, circular
or other shape and patch elements respectively disposed in each of the
slots in the form of a floating island so that a highly precise etching
will be required therefor with required etching pattern of the radiation
plate made much complicated, and there have arisen such problems that
manufacturing fluctuation becomes large to lower the yield or resultant
products and required manufacturing costs are generally elevated. In
addition, in the planar antenna of the U.S. patent, in particular, there
has been a drawback that applicable radio wave band is relatively narrow
so that, while they may be effectively utilized with respect to the
broadcasting satellite the transmission power of which is relatively
large, the reception efficiency has to be lowered when the transmission
power is relatively small in such case as the communication satellite.
Further, similar teachings to that of this U.S. patent has been disclosed
in U.S. Pat. No. 4,761,654 to A. L. Zaghloul and in U.S. Pat. No.
4,922,263 to G. Dubost et al. However, they still involve substantially
the same problems as in the above.
In order to solve the foregoing problems, the present inventors K.
Tsukamoto et al. have suggested prior to the present invention, as
disclosed in U.S. patent application Ser. No. 07/509,820, a planar antenna
in which the radiation circuit is provided with many apertures which are
generally star-shaped, the power supply terminals of the power supply
circuit are disposed to oppose respectively each of the star-shaped
apertures, and the radiation and power supply circuits are assembled with
the grounding conductor plate as separated from one another. According to
this planar antenna, it is made possible to receive the circularly
polarized waves at a high gain over a wide band. However, there has not
been suggested as yet a planar antenna which is capable of receiving over
a wide band and at a high gain the linearly polarized waves not only from
the broadcasting satellite but also from the communication satellite, and
it has been a demand that such planar antenna is developed.
SUMMARY OF THE INVENTION
A primary object of the present invention is, therefore, to provide a
planar antenna capable of receiving the linearly polarized waves over a
wide band and at a high gain.
It is another object of the present invention to provide a planar antenna
which can operate at a high efficiency so as to be able to restrain the
power supply loss to be the minimum, so that the linearly polarized waves
transmitted not only from the broadcasting satellite but also from the
communication satellite of the relatively smaller transmission power can
be received, so as to be high in the utility for various purposes.
Still another object of the present invention is to provide a planar
antenna which has a low loss interposition disposed as a dielectric member
between the respective radiation plate, power supply circuit plate and
grounding conductor plate, so as to achieve a further improved efficiency.
According to the present invention, these objects can be realized by means
of a planar antenna for linearly polarized waves, which comprising a
grounding conductor plate, a power supply circuit plate having thereon a
power supply circuit pattern including power supply terminals and disposed
to be separated from the grounding conductor plate by a predetermined
space so as to have an insulating layer interposed with respect to the
grounding conductor plate, and a radiation plate having therein apertures
disposed as radiation elements respectively coupled electromagnetically
with each of the power supply terminals of the power supply circuit plate
and disposed to be separated from the power supply circuit plate by a
predetermined space so as to have an insulating layer interposed with
respect to the power supply circuit plate, wherein the power supply
terminals of the power supply circuit plate are disposed to terminate
within a contour of the respective apertures in the top plan view.
According to the present invention, further, there is provided a planar
antenna in which the power supply circuit pattern of the power supply
circuit plate having the power supply terminals to be electromagnetically
coupled with the apertures of the radiation plate is made smaller in
conductor strip width of the pattern at portions adjacent to the terminals
to be electromagnetically coupled to the apertures of the radiation plate.
Further according to the present invention, there can be provided a planar
antenna which is made to be of a low loss by means of an insulating sheet
including many hollow swellings made to closely stand and sealing tightly
therein air as a dielectric member, the insulating sheet being disposed
between the respective radiation, power supply circuit and grounding
conductor plates.
Other objects and advantages of the present invention will be made clear in
following description of the invention detailed with reference to
accompanying drawings.
BRIEF EXPLANATION OF THE DRAWINGS
FIG. 1 is a perspective view as disassembled of the planar antenna for
linearly polarized waves in an embodiment of the present invention, with a
portion shown as removed;
FIG. 2 is a fragmentary perspective view as magnified of the planar antenna
of FIG. 1;
FIG. 3 is a fragmentary sectioned view as magnified of the planar antenna
of FIG. 1;
FIG. 4 is a fragmentary sectioned view as magnified of the planar antenna
of FIG. 1 but in another aspect thereof;
FIG. 5 is an explanatory view for the relationship between the aperture and
the power supply terminal in the planar antenna of FIG. 1;
FIG. 6 is an explanatory view for the relationship between the aperture and
the power supply terminal in another aspect of the planar antenna of FIG.
1;
FIG. 7 is a diagram showing the relationship between the frequency and the
return loss in the planar antenna of FIG. 1;
FIG. 8 is a diagram showing the relationship between the frequency and the
antenna efficiency in the planar antenna of FIG. 1;
FIG. 9 is a plan view of the power supply circuit pattern in another
embodiment of the planar antenna according to the present invention;
FIG. 10 is a fragmentary perspective view as magnified of the planar
antenna in still another embodiment according to the present invention;
FIG. 11 is a fragmentary sectioned view of the insulating sheet employed in
the planar antenna of FIG. 10; and
FIG. 12 is a fragmentary sectioned view as magnified of the planar antenna
of FIG. 10.
While the present invention shall now be explained with reference to the
embodiments shown in the accompanying drawings, it will be appreciated
that the intention is not to limit the present invention only to these
embodiments shown but rather to include all alterations, modifications and
equivalent arrangements possible within the scope of appended claims of
the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIGS. 1 to 3 showing the planar antenna for linearly polarized
waves in an embodiment according to the present invention, the planar
antenna 10 generally comprises a grounding conductor plate 11, a power
supply circuit plate 12, and a radiation plate 13. The grounding conductor
plate 11 can be formed with an aluminum plate of a thickness of about 2
mm, for example, while such other electrically conducting material as
copper, silver, astatine, iron, gold or the like may also be utilized. In
the power supply circuit plate 12, a power supply circuit pattern 14 of
conductor strips of such conducting material as copper, aluminum, silver,
astatine, iron, gold or the like, preferably, is formed by means of an
etching on a plastic sheet which is formed with polyethylene,
polypropylene, polyester, acryl, polycarbonate, ABS resin or PVC resin
alone or in a mixture of two or more, preferably. The radiation plate 13
is formed with an aluminum plate of a thickness of about 0.4 mm,
preferably, with a plurality of apertures 15 formed as radiation elements
by means of punching.
The apertures 15 in the radiation plate 13 are formed to have a
square-shaped contour (see FIG. 5) and are arranged in column and line
relationship. The power supply circuit pattern 14 on the power supply
circuit plate 12 is so formed as to dispose power supply terminals 16 of
the pattern 14 respectively at a position aligned with each of the
apertures 15 of the radiation plate 13 so that, in the present instance,
the power supply terminal 16 will extend beyond the center of the aperture
15 in plan view but terminate at a position within the square-shaped
contour, without exceeding the contour, whereby the power supply terminals
16 are enabled to be optimumly coupled electromagnetically to the
apertures 15 and hence the linearly polarized waves from the satellite are
enabled to be effectively received. Further, a highly efficient antenna
gain may be attained when the apertures 15 are formed by the punching in
32 columns and 32 lines at intervals of 20 mm, for example.
In the embodiment of FIGS. 1 to 3, the arrangement has been made to
interpose the air layer between the respective grounding conductive plate
11, power supply circuit plate 12 and radiation plate 13 for their mutual
electric insulation, but such insulation may be similarly achieved by
means of such interpositions 17 made of foamed plastic and inserted
between the respective plates 11, 12 and 13 as shown in FIG. 4. Further,
while the apertures 15 of the radiation plate 13 should be formed
preferably to have the square-shaped contour as shown in FIG. 5 for
achieving the highly efficient gain with the aperture area thus enlarged,
the radiation plate 13 may be formed to have such circular apertures 15a
as shown in FIG. 6 to be combined with the power supply terminals 16 which
are also disposed to extend beyond the center of the circular apertures
15a but to terminate within circular contour of the apertures 15a in the
plan view.
In the planar antenna 10 of the foregoing arrangement, it has been found
that the return loss with respect to the frequency is shown to be
excellent even when the frequency is around 11 GHz and 13 GHz, as seen in
FIG. 7. Further, as shown in FIG. 8 by a curve "x", the antenna efficiency
with respect to the frequency is excellent over a range of 11 to 13 GHz,
to be better than that of known arrangement as shown by a curve "y".
EXAMPLE 1
First, the square-shaped apertures of 15 mm at each side were formed as
being punched through an aluminum plate of 0.5 mm thick and available in
the market, so as to be the radiation elements in 32 columns and 32 lines,
and thereby the radiation plate was obtained. Next, the power supply
circuit plate was prepared by forming the power supply circuit pattern
having the power supply terminals for the electromagnetic coupling with
the apertures as the radiation elements, on a flexible printed-circuit
substrate available in the market, by means of an etching. Further, this
power supply circuit plate was mounted on the grounding conductive plate
of an aluminum plate of 2 mm thick and available in the market, with a
foamed polyethylene sheet of 1 mm thick and available in the market
interposed between these plates, the radiation plate was further stacked
on the power supply circuit plate with a further foamed polyethylene sheet
of 3 mm thick and available in the market as interposed between them, and
a planar antenna for the linearly polarized waves was thereby prepared.
It was found that, with the above planar antenna, the antenna efficiency of
more than 65% was obtained at least over 11 to 13 GHz.
EXAMPLE 2
Except that the apertures of the radiation plate were made circular instead
of the square shape, a planar antenna for the linearly polarized waves was
prepared in the same manner as in Example 1. While the antenna efficiency
was slightly lower than that of Example 1, this planar antenna could also
attain the antenna efficiency of more than 65% over the range of 11 to 13
GHz.
EXAMPLE 3
A planar antenna for the linearly polarized waves was prepared by employing
a foamed polyethylene sheet of 2 mm thick in place of the 1 mm thick
foamed polyethylene sheet between the radiation plate and the power supply
circuit plate in the foregoing Example 1, as well as a foamed polyethylene
sheet of 4 mm thick in place of the 3 mm thick foamed polyethylene sheet
between the power supply circuit plate and the grounding conductor plate.
It was found that, with this arrangement of the planar antenna, the
antenna efficiency could be improved substantially by about 3%, and the
frequency band could be also widened by 500MHz.
EXAMPLE 4
A planar antenna for the linearly polarized waves was prepared by employing
foamed polyethylene sheets of 2 mm thick in place of both the 1 mm thick
foamed polyethylene sheet between the radiation and power supply circuit
plates and the 3 mm thick foamed polyethylene sheet between the power
supply circuit and grounding conductor plates in the foregoing Example 1,
and it was also found that this planar antenna could attain the same
effect as in the planar antenna of the foregoing Example 1.
EXAMPLE 5
A planar antenna for the linearly polarized waves was prepared in the same
manner as in the foregoing Example 1 except for that the radiation plate
was formed with a flexible printed-circuit substrate having thereon a
conductor film including the apertures formed by means of an etching
instead of the punching, and substantially the same effect as in the
planar antenna of Example 1 could be attained.
According to another feature of the present invention, the planar antenna
for the linearly polarized waves is arranged for minimizing the power
supply loss in the power supply circuit pattern. Referring to FIG. 9, a
power supply circuit pattern 14A formed on a power supply circuit plate
12A by means of, for example, etching is made to be relatively smaller in
the conductor strip width in such areas 18A as enclosed by dotted lines in
the drawing than that in other areas 19A and power supply terminals 16A,
the areas 18A being located adjacent to the power supply terminals 16A to
be electromagnetically coupled with the apertures forming the radiation
elements in the radiation plate and preferably including at least first
and second T-shaped branch portions from the terminals 16A. In this case,
the conductor strips of the smaller width in the areas 18A and other
conductor strips of relatively larger width are disposed to run in
parallel relationship with intervals set to be larger than the smaller
width of the conductor strips in the areas 18A.
It has been found that, with the above arrangement of the instant
embodiment, an undesirable electromagnetic coupling of the apertures with
such other portions of the power supply circuit pattern 14A than the
terminals 16A could be restrained to be the minimum. In practice, the
planar antenna for the linearly polarized waves of the instant embodiment
has shown to be improved in the gain by 0.5 dB, in contrast to the planar
antenna for the linearly polarized waves in which the conductor strip
width of the power supply circuit pattern 14A is kept substantially the
same all over the pattern. It could be also possible to attain a higher
antenna efficiency than that in the foregoing embodiment of FIGS. 1 to 3
over such wider band as to be 11 to 13 GHz.
According to still another feature of the present invention, it is
attempted to improve the antenna efficiency by inserting interpositions
showing a low loss between the grounding conductor plate and the power
supply circuit plate and between the power supply circuit plate and the
radiation plate. Referring to FIGS. 10 to 12, a first insulating sheet
17B1 carrying hollow swellings is inserted between the grounding conductor
plate 11B of the conducting material and the power supply circuit plate
12B carrying the power supply circuit pattern 14B including the power
supply terminals 16B, and a second insulating sheet 17B2 carrying also the
hollow swellings is inserted between the power supply circuit plate 12B
and the radiation plate 13B having the apertures 15B. The first and second
insulating sheets 17B1 and 17B2 comprise a plastic sheet formed to have on
one side many swellings 20B1 and 20B2 in which air is tightly sealed,
while these swellings 20B1 and 20B2 may be formed in the external form to
be a circular truncated cone shape, circular cylindrical shape, spherical
shape, dome shape, frustum-of-pyramid shape, square cylindrical shape or
any other shape equivalent to them. In the planar antenna 10B for the
linearly polarized waves formed with such sheets 17B1 and 17B2, as seen
particular in FIG. 12, the respective swellings 20B1 and 20B2 are disposed
between the grounding conductor plate 11B and the power supply circuit
plate 12B and between the power supply circuit plate 12B and the radiation
plate 13B, so as to function to optimumly separate these plates by a
predetermined interval. In this arrangement, it will be readily
appreciated that the first insulating sheet 17B1 may be so inserted as to
abut top faces of the swellings 20B1 against the grounding conductor plate
11B, i.e., as turned over from the state of FIG. 12.
According to the instant embodiment, the use of the plastic sheet having
the air-sealed swellings is effective to elevate the existing percentage
of air between the respective grounding conductor plate, power supply
circuit plate and radiation plate, i.e., effective to lower the existing
percentage of the dielectric material, whereby the dielectric loss can be
reduced and the antenna efficiency can be remarkably improved.
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